Biosimilar Battle: Sandoz vs. Amgen – A Legal Clash with Billion-Dollar Stakes

In early 2025, Sandoz, the generics arm of Novartis, escalated its rivalry with Amgen by filing a landmark antitrust lawsuit in U.S. federal court. The case centers on Amgen’s alleged use of a “thicket of patents” to block Sandoz’s biosimilar Erelzi from competing with its blockbuster drug Enbrel. This legal showdown not only threatens Amgen’s $3.3 billion annual U.S. revenue stream but also raises critical questions about patent strategies in the biologics market and their impact on drug pricing. For investors, the outcome could redefine competitive dynamics in a sector where monopolies and generics are locked in a perpetual tug-of-war.

The Legal Landscape: A Decade of Delay

Sandoz’s lawsuit accuses Amgen of anticompetitive behavior by leveraging patents to extend Enbrel’s market exclusivity until 2029, despite the drug’s original FDA approval dating back to 1998. The crux of the complaint is Amgen’s alleged exploitation of “evergreening” tactics—filed patents that incrementally extend protection without significant innovation. Sandoz argues this practice violates antitrust laws by stifling biosimilar competition and inflating drug costs for millions of Americans living with autoimmune diseases.

The case hinges on whether Amgen’s patent portfolio constitutes an unlawful barrier to entry. Sandoz highlights its own rigorous development of Erelzi, including a Phase III trial demonstrating equivalence to Enbrel, and estimates that delayed market entry has cost it millions in monthly sales. The lawsuit seeks both an injunction to remove these barriers and treble damages under the Sherman Antitrust Act, which could amplify financial penalties if successful.

Market Impact: The $3.3 Billion Prize

Enbrel’s dominance in treating conditions like rheumatoid arthritis and psoriasis makes it a critical revenue driver for Amgen. With U.S. sales of $3.3 billion in 2024 alone, losing even a fraction of this market to biosimilars could significantly dent Amgen’s profit margins. Sandoz, meanwhile, has waited nearly a decade to enter the U.S. market after securing FDA approval in 2016—Erelzi has been available in Europe since 2015.

The lawsuit underscores a broader industry trend: biosimilars are increasingly challenging biologic monopolies, but patent disputes often delay this process. For example, Amgen’s 2029 patent expiration date for Enbrel is nearly a decade later than initial biosimilar approvals in Europe, highlighting the strategic use of patents to prolong exclusivity.

Financial Implications: Winners and Losers

If Sandoz prevails, the immediate beneficiary would be Novartis, whose generics division has struggled to replicate European biosimilar success in the U.S. market. Analysts estimate Erelzi could capture 20–30% of Enbrel’s U.S. sales within three years, adding hundreds of millions to Novartis’ bottom line. Conversely, Amgen’s shares could face pressure if investors anticipate revenue erosion.

However, the case’s complexity introduces uncertainty. Amgen has historically defended its patents aggressively, and patent litigation often drags on for years. Even if Sandoz wins an injunction, the path to market entry could remain fraught with appeals. Meanwhile, treble damages—potentially in the billions—add another layer of risk for Amgen.

Broader Industry Implications: A Precedent for Antitrust Enforcement

The lawsuit’s significance extends beyond these two companies. The U.S. Department of Justice has recently intensified scrutiny of pharmaceutical patent strategies, signaling a shift toward stricter antitrust enforcement in healthcare. A ruling in Sandoz’s favor could embolden other biosimilar manufacturers to challenge entrenched biologic monopolies, accelerating price competition. Conversely, a loss might reinforce the legitimacy of aggressive patenting as a defensive tool.

Investors should also monitor regulatory developments. The FDA’s recent push to fast-track biosimilar approvals—such as its “patent dance” reforms—could complement legal victories like this one in dismantling barriers to competition.

Conclusion: A Tipping Point for Biosimilars?

The Sandoz v. Amgen case is a microcosm of the pharmaceutical industry’s struggle between innovation and affordability. With Enbrel’s U.S. sales at $3.3 billion in 2024 and Sandoz estimating millions in lost revenue annually, the financial stakes are immense. A win for Sandoz would not only unlock immediate gains for Novartis but also set a precedent that could disrupt the biologics market’s patent-driven economics.

For Amgen, the lawsuit represents a test of its patent strategy’s resilience. While the stock has historically shrugged off biosimilar threats (as seen in its 5-year outperformance of Novartis), a loss here could trigger a reevaluation of its growth trajectory. Meanwhile, investors in generics and biosimilars should take note: this case may determine whether antitrust law becomes a game-changer in curbing monopolistic practices.

The verdict won’t come soon, but the implications are clear: the era of indefinite biologic monopolies may be ending. For patients and investors alike, the outcome could redefine access to healthcare—and the profitability of pharmaceutical giants.